Dr. Tracy Becker Honored with 2023 Carl Sagan Medal for Science Communication

2023 Carl Sagan Medal recipient, Dr. Tracy Becker, who is a group leader in the Southwest Research Institute’s Space Science Division. Dr. Becker is a planetary scientist whose research interests include remote observations of space phenomena such as the asteroid system shown here. (Credit: Southwest Research Institute)

This year’s prestigious Carl Sagan Medal, also known as the “Sagan Medal” and named after the late astronomer, Dr. Carl Sagan, has been awarded to Dr. Tracy Becker, who is a planetary scientist in the Space Science Division of the Southwest Research Institute (SwRI) in San Antonio, Texas. The Sagan Medal recipient is chosen by the Division for Planetary Sciences of the American Astronomical Society (AAS) and is meant to acknowledge planetary scientists who are not only active in science communication with the general public but have taken enormous strides in helping the general public better understand, and get excited for, the field of planetary science.

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Why ‘Contact’ still resonates after 25 years

Credit: Fuawas; permission to share under the under the Creative Commons Attribution-Share Alike 4.0 International license.

25 years ago, the film Contact made its theatrical debut starring Jodie Foster and Matthew McConaughey and told the story of Dr. Eleanor Arroway (Jodie Foster) who picked up a radio signal from the star Vega and how this discovery impacted not just herself, but humanity as a whole. Over time, she discovers the signal has embedded instructions sent by the aliens to build a device capable of sending one person into outer space, presumably to meet the Vegans.

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60 Years Later, is it Time to Update the Drake Equation?

The Drake Equation, a mathematical formula for the probability of finding life or advanced civilizations in the universe. Credit: University of Rochester

On November 1st, 1961, a number of prominent scientists converged on the National Radio Astronomy Observatory in Green Bank, West Virginia, for a three-day conference. A year earlier, this facility had been the site of the first modern SETI experiment (Project Ozma), where famed astronomers Frank Drake and Carl Sagan used the Green Bank telescope (aka. “Big Ear”) to monitor two nearby Sun-like stars – Epsilon Eridani and Tau Ceti.

While unsuccessful, Ozma became a focal point for scientists who were interested in this burgeoning field known as the Search for Extraterrestrial Intelligence (SETI). As a result, Drake and Sagan were motivated to hold the very first SETI conference, wherein the subject of looking for possible extraterrestrial radio signals would be discussed. In preparation for the meeting, Drake prepared the following heuristic equation:

N = R* x fp x ne x fl x fi x fc x L

This would come to be known as the “Drake Equation,” which is considered by many to be one of the most renowned equations in the history of science. On the sixtieth anniversary of its creation, John Gertz – a film producer, amateur astronomer, board-member with BreakThrough Listen, and the three-term former chairman of the board for the SETI Institute – argues in a recent paper that a factor by factor reconsideration is in order.

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How Much Life Would Be Required to Create the Phosphine Signal on Venus?

How can astronomers tell exo-Earths and exo-Venuses apart? Polarimetry might be the key. Image Credits: NASA

A Biosignature

Last week, an incredible announcement was made about the search for extraterrestrial life: Phosphine gas detected in the clouds of Venus – a potential indicator of life or “biosignature.” Now some gases might be a false positive for biosignatures because they can be created by other chemical processes on a planet like photochemical processes in the atmosphere or geological processes beneath the surface that create a given gas. For example, methane can also be a biosignature, and we’ve been hunting it down on Mars, but we know that methane can also be created geologically. Finding phosphine in Venusian clouds is truly remarkable because we don’t presently know of any way to create phosphine abiotically or without life being a part of the equation. Question is – how much life??

Clouds of Venus as seen from Mariner 10’s flyby – NASA
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Beyond “Fermi’s Paradox” IX: What is the Brief Window Hypothesis?

A case study of the inhabitants of Easter Island served in part as the basis for a mathematical model showing the ways a technologically advanced population and its planet might develop or collapse together. Credit: University of Rochester illustration / Michael Osadciw

Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the possibility that we haven’t heard from aliens because intelligent life only survives for so long.

In 1950, Italian-American physicist Enrico Fermi sat down to lunch with some of his colleagues at the Los Alamos National Laboratory, where he had worked five years prior as part of the Manhattan Project. According to various accounts, the conversation turned to aliens and the recent spate of UFOs. Into this, Fermi issued a statement that would go down in the annals of history: “Where is everybody?

This became the basis of the Fermi Paradox, which refers to the disparity between high probability estimates for the existence of extraterrestrial intelligence (ETI) and the apparent lack of evidence. Since Fermi’s time, there have been several proposed resolutions to his question, which include the possibility that civilizations only have a “Brief Window” with which to communicate with the cosmos before going extinct.

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Beyond “Fermi’s Paradox” III: What is the Great Filter?

The Karl Jansky Very Large Array at night, with the Milky Way visible in the sky. Credit: NRAO/AUI/NSF; J. Hellerman

Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the possibility that there is something in the Universe that prevents life from reaching the point where we would be able to hear from it.

In 1950, Italian-American physicist Enrico Fermi sat down to lunch with some of his colleagues at the Los Alamos National Laboratory, where he had worked five years prior as part of the Manhattan Project. According to various accounts, the conversation turned to aliens and the recent spate of UFOs. Into this, Fermi issued a statement that would go down in the annals of history: “Where is everybody?

This became the basis of the Fermi Paradox, which refers to the high probability estimates for the existence of extraterrestrial intelligence (ETI) and the apparent lack of evidence. Seventy years later, we still haven’t answered that question, which has led to many theories as to why the “Great Silence” endures. A popular one is that there must be “Great Filter” that prevents life from reaching an advanced stage of development.

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Could There Be Life in the Cloudtops of Venus?

According to a new study, microbial life could exist in Venus' cloud tops, where temperature and pressure conditions are favorable. Credit: NASA

In the search for life beyond Earth, scientists have turned up some very interesting possibilities and clues. On Mars, there are currently eight functioning robotic missions on the surface of or in orbit investigating the possibility of past (and possibly present) microbial life. Multiple missions are also being planned to explore moons like Titan, Europa, and Enceladus for signs of methanogenic or extreme life.

But what about Earth’s closest neighboring planet, Venus? While conditions on its surface are far too hostile for life as we know it there are those who think it could exist in its atmosphere. In a new study, a team of international researchers addressed the possibility that microbial life could be found in Venus’ cloud tops. This study could answer an enduring mystery about Venus’ atmosphere and lead to future missions to Earth’s “Sister Planet”.

The study, titled “Venus’ Spectral Signatures and the Potential for Life in the Clouds“, recently appeared in the journal Astrobiology. The study was led by Sanjay Limaye of the University of Wisconsin-Madison’s Space Science and Engineering Center and included members from NASA’s Ames Research Center, NASA’s Jet Propulsion Laboratory, California State Polytechnic University, the Birbal Sahni Institute of Palaeosciences, and the University of Zielona Góra.

Artist’s impression of the surface of Venus, showing its lightning storms and a volcano in the distance. Credit and ©: European Space Agency/J. Whatmore

For the sake of their study, the team considered the presence of UV contrasts in Venus’ upper atmosphere. These dark patches have been a mystery since they were first observered nearly a century ago by ground-based telescopes.  Since then, scientists have learned that they are made up of concentrated sulfuric acid and other unknown light-absorbing particles, which the team argues could be microbial life.

As Limaye indicated in a recent University of Wisconsin-Madison press statement:

“Venus shows some episodic dark, sulfuric rich patches, with contrasts up to 30 – 40 percent in the ultraviolet, and muted in longer wavelengths. These patches persist for days, changing their shape and contrasts continuously and appear to be scale dependent.”

To illustrate the possibility that these streaks are the result of microbial life, the team considered whether or not extreme bacteria could survive in Venus’ cloud tops. For instance, the lower cloud tops of Venus (47.5 to 50.5 km above the surface) are known to have moderate temperature conditions (~60 °C; 140 °F) and pressure conditions that are similar to that of Earth at sea level (101.325 kPa).

This is far more hospitable than conditions on the surface, where temperatures reach 737 K (462 C; 860 F) and atmospheric pressure is 9200 kPa (92 times that of Earth at sea level). In addition, they considered how on Earth, bacteria has been found at altitudes as high as 41 km (25 mi). On top of that, there are many cases where extreme bacteria here on Earth that could survive in an acidic environment.

A composite image of the planet Venus as seen by the Japanese probe Akatsuki. The clouds of Venus could have environmental conditions conducive to microbial life. Credit: JAXA/Institute of Space and Astronautical Science

As Rakesh Mogul, a professor of biological chemistry at California State Polytechnic University and a co-author on the study, indicated, “On Earth, we know that life can thrive in very acidic conditions, can feed on carbon dioxide, and produce sulfuric acid.” This is consistent with the presence of micron-sized sulfuric acid aerosols in Venus upper atmosphere, which could be a metabolic by-product.

In addition, the team also noted that according to some models, Venus had a habitable climate with liquid water on its surface for as long as two billion years – which is much longer than what is believed to have occurred on Mars. In short, they speculate that life could have evolved on the surface of Venus and been swept up into the atmosphere, where it survived as the planet experienced its runaway greenhouse effect.

This study expands on a proposal originally made by Harold Morowitz and famed astronomer Carl Sagan in 1967 and which was investigated by a series of probes sent to Venus between 1962 and 1978. While these missions indicated that surface conditions on Venus ruled out the possibility of life, they also noted that conditions in the lower and middle portions of Venus’ atmosphere – 40 to 60 km (25 – 27 mi) altitude – did not preclude the possibility of microbial life.

For years, Limaye has been revisiting the idea of exploring Venus’ atmosphere for signs of life. The inspiration came in part from a chance meeting at a teachers workshop with Grzegorz Slowik – from the University of Zielona Góra in Poland and a co-author on the study – who told him of how bacteria on Earth have light-absorbing properties similar to the particles that make up the dark patches observed in Venus’ clouds.

Aircraft like the Venus Atmospheric Maneuverable Platform (VAMP) could explore the cloud tops of Venus for possible signs of life. Credit: Northrop Grumman Corp

While no probe that has sampled Venus’ atmosphere has been capable of distinguishing between organic and inorganic particles, the ones that make up Venus’ dark patches do have comparable dimensions to some bacteria on Earth. According to Limaye and Mogul, these patches could therefore be similar to algae blooms on Earth, consisting of bacteria that metabolizes the carbon dioxide in Venus’ atmosphere and produces sulfuric acid aerosols.

In the coming years, Venus’ atmosphere could be explored for signs of microbial life by a lighter than air aircraft. One possibility is the Venus Aerial Mobil Platform (VAMP), a concept currently being researched by Northrop Grumman (shown above). Much like lighter-than-air concepts being developed to explore Titan, this vehicle would float and fly around in Venus’ atmosphere and search the cloud tops for biosignatures.

Another possibility is NASA’s possible participation in the Russian Venera-D mission, which is currently scheduled to explore Venus during the late 2020s. This mission would consist of a Russian orbiter and lander to explore Venus’ atmosphere and surface while NASA would contribute a surface station and maneuverable aerial platform.

Another mystery that such a mission could explore, which has a direct bearing on whether or not life may still exist on Venus, is when Venus’ liquid water evaporated. In the last billion years or so, the extensive lava flows that cover the surface have either destroyed or covered up evidence of the planet’s early history. By sampling Venus’ clouds, scientists could determine when all of the planet’s liquid water disappeared, triggering the runaway greenhouse effect that turned it into a hellish landscape.

NASA is currently investigating other concepts to explore Venus’ hostile surface and atmosphere, including an analog robot and a lander that would use a Sterling engine to turn Venus’ atmosphere into a source of power. And with enough time and resources, we might even begin contemplating building floating cities in Venus atmosphere, complete with research facilities.

Further Reading: Space Science and Engineering Center, Astrobiology

New Horizons Just Took a Record Breaking Image. No Camera Has Ever Taken a Picture From This Far From Earth

With its Long Range Reconnaissance Imager (LORRI), New Horizons has observed several Kuiper Belt objects (KBOs) and dwarf planets at unique phase angles, as well as Centaurs at extremely high phase angles to search for forward-scattering rings or dust. These December 2017 false-color images of KBOs 2012 HZ84 (left) and 2012 HE85 are, for now, the farthest from Earth ever captured by a spacecraft. They're also the closest-ever images of Kuiper Belt objects. Credits: NASA/JHUAPL/SwRI

In July of 2015, the New Horizons mission made history by being the first spacecraft to rendezvous with Pluto. In the course of conducting its flyby, the probe gathered volumes of data about Pluto’s surface, composition, atmosphere and system of moons. It also provided breathtaking images of Pluto’s “heart”, its frozen plains, mountain chains, and it’s mysterious “bladed terrain”.

Since that time, New Horizons has carried on to the Kuiper Belt for the sake of conducting more historic encounters. In preparation for these, the probe also established new records when it used its Long Range Reconnaissance Imager (LORRI) to take a series of long-distance pictures. These images, which have since been released to the public, have set the new record for the most distant images ever taken.

At present, the New Horizons probe is at a distance of 6.12 billion km (3.79 billion mi) from Earth. This means that images taken at this point are at a distance of 40.9 Astronomical Units (AUs), or the equivalent of about 41 times the distance between Earth and the Sun. This it slightly farther than the “Pale Blue Dot” image of Earth, which was snapped by the Voyager 1 mission when it was at a distance of 6.06 billion km (3.75 billion mi; 40.5 AU) from Earth.

Image of the “Wishing Well” star cluster, taken Dec. 5, 2017, which temporarily broke the 27-year record set by Voyager 1. Credit: NASA/JHUAPL/SwRI

This historic picture was taken on February 14th, 1990 (Valentine’s Day) at the behest of famed astronomer Carl Sagan. At the time, Sagan was a member of the Voyager imaging team, and he recommended that Voyager 1 take the opportunity to look back at Earth one more time before making its way to the very edge of the Solar System. For more than 27 years, this long-distance record remained unchallenged.

However, in December of 2017, the New Horizons team began conducting a routine calibration test of the LORRI instrument. This consisted of snapping pictures of the “Wishing Well” cluster (aka. the “Football Cluster” or NGC 3532), an open galactic star cluster that is located about 1321 light years from Earth in the direction of the southern constellation of Carina.

This image (shown above) was rather significant, given that this star cluster was the first target ever observed by the Hubble Space Telescope (on May 20th, 1990). While this image broke the long-distance record established by Voyager 1, the probe then turned its LORRI instrument towards objects in its flight path. As part of the probes mission to rendezvous with a KBO, the team was searching for forward-scattering rings or dust.

As a result, just two hours after it had taken the record-breaking image of the “Wishing Well” star cluster, the probe snapped pictures of the Kuiper Belt Objects (KBOs) known as 2012 HZ84 and 2012 HE85 (seen below, left and right). These images once again broke the record for being the most distant images taken from Earth (again), but also set a new record for the closest-ever images ever taken of KBOs.

False-color images of KBOs 2012 HZ84 (left) and 2012 HE85, taken by LORRI, are the farthest from Earth ever captured by a spacecraft. Credit: NASA/JHUAPL/SwRI

As Dr. Alan Stern, the Principle Investigator of the New Horizons mission at the Southwest Research Institute (SwRI), explained in a NASA press release:

“New Horizons has long been a mission of firsts — first to explore Pluto, first to explore the Kuiper Belt, fastest spacecraft ever launched. And now, we’ve been able to make images farther from Earth than any spacecraft in history.”

As one of only five spacecraft to travel beyond the Outer Planets, New Horizons has set a number of other distance records as well. These include the most-distant course-correction maneuver, which took place on Dec. 9th, 2017, and guided the spacecraft towards its planned flyby with the KBO 2014 MU69. This event, which will happen on Jan. 1st, 2019, will be the farthest planetary encounter in history.

In the course of its extended mission in the Kuiper Belt, the New Horizons team seeks to observe at least two-dozen other KBOs, dwarf planets and “Centaurs” – i.e. former KBOs that have unstable orbits that cause them to cross the orbit of the gas giants. At present, the New Horizons spacecraft is in hibernation and will be brought back online on June 4th, – when it will begin a series of checks to make sure it is ready for its planned encounter with MU69.

The spacecraft is also conducting nearly continuous measurements of the Kuiper Belt itself to learn more about its plasma, dust and neutral-gas environment. These efforts could reveal much about the formation and evolution of the Solar System, and are setting records that are not likely to be broken for many more decades!

Further Reading: NASA

Carl Sagan’s Crazy Idea: Life Inside A Comet?

Comet 2012 S1 ISON in outburst, seen on November 15, 2013. Credit and copyright: Damian Peach.

Establishing a sustained human presence somewhere other than Earth is a vital part of humanity’s future, no matter what. We know that Earth won’t last forever. We don’t know exactly which one of the many threats that Earth faces will ultimately extinguish life here, but life will be extinguished completely at some future point.

Colonizing moons or planets is one way to do it. But that’s really hard. We may make it to Mars before too long, but we don’t know how successful we’ll be at establishing a presence there. There are an awful lot of ‘ifs’ when it comes to Mars.

The only other option is space habitats. That makes sense; there’s much more space out there than there is surface area on planets and moons. And space habitats have been on the minds of thinkers, writers, and scientists for a long time.

Gerard K. O’Neill is probably the most well-known thinker when it comes to space habitats. In 1977 he published the seminal book on space habitats, called “The High Frontier: Human Colonies in Space.” O’Neill in his time popularized what is now called the “O’Neill Cylinder.”

The O’Neill Cylinder

Interior view of an O'Neill Cylinder. There are alternating strips of livable surface and "windows" to let light in. Image: Rick Guidice, NASA Ames Research Center
Interior view of an O’Neill Cylinder. There are alternating strips of livable surface and “windows” to let light in. Image: Rick Guidice, NASA Ames Research Center

The O’Neill Cylinder lay the groundwork for space habitat design. It consisted of two counter-rotating cylinders, one nested inside the other. The counter-rotation provided stability and gravity. The atmosphere would be controlled, and the habitat would be powered by solar, and perhaps fusion.

An illustration of two O'Neill Cylinder's. Image: Rick Guidice NASA Ames Research Center
An illustration of two O’Neill Cylinder’s. Image: Rick Guidice NASA Ames Research Center

The McKendree Cylinder

Other designs from other people followed O’Neill’s. Notable among them is the McKendree Cylinder. The McKendree would be gargantuan compared to the O’Neill Cylinder. Thanks to carbon nanotubes, it would have more surface area than the United States. It was designed by NASA Engineer Tom McKendree and introduced in the year 2,000 at the NASA “Turning Goals into Reality Conference.”

There’ve been other ideas for massive, high-tech space habitats, including the Bernal Sphere and the Stanford Torus. All of these designs are typical of engineers and technologists. Lots of high-tech, lots of steel, lots of machinery. But the engineers and scientists behind those designs weren’t the only ones thinking about humans in space.

Carl Sagan was too. And he had a very different idea of what space habitats could be.

So Crazy It Just Might Work

But the craziest idea for space habitats has got to be Carl Sagan’s, from his 1985 book “Comet.”In “Comet” Sagan suggested that humans could seek refuge in, and even colonize, actual comets travelling through our Solar System. Using all the advanced technologies thought about in Sagan’s time—but which don’t exist yet—comets could be transformed into humanity’s salvation. His idea is a world apart from the high-tech, highly-engineered, gleaming habitat designs that most people think of when they think of space habitats.

I’m a fan of Sagan’s. Like many in my generation, I was influenced by his TV series Cosmos. I loved it and it’s stuck with me. His book “The Demon-Haunted World” taught us what scientific skepticism can be, and how useful it is.

"Comet" was published only months before Halley's Comet arrived in our inner Solar System in 1986. Image: Jon Lomberg, Random House New York.
“Comet” was published only months before Halley’s Comet arrived in our inner Solar System in 1986. Image: Jon Lomberg, Random House New York.

Sagan’s is the most surprising—and perhaps bleakest—view of space habitats. Life inside comets sounds shocking, and maybe even foolish, but as Sagan explains, there is some reasoning behind the idea.

Remember that when Sagan wrote about this, thermonuclear war between the superpowers was a “thing,” and thinkers like Sagan felt a sense of imminent danger. That sense of foreboding may have contributed to his “comets-as-space-habitas” idea. Plus, he was just an innovative thinker.

Carl Sagan in 1980.
Carl Sagan in 1980.

Sagan’s thinking behind using comets as space habitats starts out something like this: if there are about a hundred thousand comets crossing Earth’s orbit, and another hundred trillion in the Oort Cloud, their combined surface area is roughly equal to about a hundred million Earths. And with advanced technology, Sagan proposed that these comets could be captured and colonized and sent on orbits and trajectories desirable to humans.

Comet Lovejoy and its spectacular "lively" ion tail photographed on January 8th by Nick Howes at Tzec Muan Network at Siding Spring Australia. Could Lovejoy and its brethren one day provide a home for humanity?
Comet Lovejoy and its spectacular “lively” ion tail photographed on January 8th by Nick Howes at Tzec Muan Network at Siding Spring Australia. Could Lovejoy and its brethren one day provide a home for humanity?

Comets are rich in minerals, water ice, and biological compounds. Or so it was thought at the time. That means raw material for manufacturing, water to drink and to supply oxygen, biological compounds for bio-engineering, and even the raw material for rocket fuel. Add a fusion reactor for power, and
comets could end up being the convenience stores of the Solar System.

Physicist Freeman Dyson, an innovative thinker himself, had something to add to Sagan’s comet idea. In “Comet,” Sagan tells of Dyson’s ideas around genetic engineering, and that one day we should be able to engineer forms of life that could thrive on comets, and meet some of our needs. Dyson talks about a giant, genetically engineered tree that could grow on a comet, planted in snow rich in organic chemicals. The tree would supply us with fresh oxygen.

The OSIRIS narrow-angle camera aboard the Rosetta spacecraft captured this image of comet 67P/Churyumov-Gerasimenko on September 30, 2016. Does it look habitable, or potentially habitable, to you? Credits: ESA/Rosetta/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
The OSIRIS narrow-angle camera aboard the Rosetta spacecraft captured this image of comet 67P/Churyumov-Gerasimenko on September 30, 2016. Does it look habitable, or potentially habitable, to you? Credits: ESA/Rosetta/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

This sounds extremely far-fetched: humans living inside comets travelling through space, with giant genetically engineered trees and fusion power plants. I try to remind myself that many things we take for granted now were once thought to be laughable. But even though parts of the comet-as-space-habitat idea sound fanciful—like the giant tree—there may be the seed of a practical idea here, with humans hitching rides on comets, molding them to our purposes, and extracting resources like minerals and fuel from them.

High cliffs on the surface of Comet Churyumov–Gerasimenko as imaged by the Rosetta spacecraft. Image Credit & Licence (CC BY-SA 3.0 IGO): ESA, Rosetta spacecraft, NAVCAM; Additional Processing: Stuart Atkinson
High cliffs on the surface of Comet Churyumov–Gerasimenko as imaged by the Rosetta spacecraft. Image Credit & Licence (CC BY-SA 3.0 IGO): ESA, Rosetta spacecraft, NAVCAM; Additional Processing: Stuart Atkinson

Sagan was an agile creative thinker. He’s clearly riffing when he outlines his ideas for life on comets. He’s like the John Coltrane of space science.

It seems doubtful that we would go to the trouble to turn comets into actual habitats. It’s probably more science fiction that science. But the future is unwritten, and given enough time, almost anything might be possible.

Where Are All The Alien Robots?

If you’ve seen at least one other episode of the Guide to Space, you know I’m obsessed about the Fermi Paradox. This idea that the Universe is big and old, and should be teeming with life. And yet, we have no evidence that it exists out there. We wonder, where are all the aliens?

Ah well, maybe we’re in a cosmic zoo, or maybe the Universe is just too big, or the laws of physics prevent any kind of meaningful travel or communications. Fine. I doubt it, but fine.

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